The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Since a DCT transmits an engine torque using a dry clutch unlike a typical automatic transmission that uses a torque converter and a wet multiple disk clutch, it is difficult for the DCT to be cooled by air during heating caused by clutch slip.
Hence, when the temperature of the DCT is increased, the DCT may not efficiently transmit power due to the considerably undermined friction performance of friction materials. Under this condition, the clutch of the DCT is worn out easily (i.e., fade-out) when the clutch slip continues to occur so that malfunction of the clutch may occur.
In the related art, a called limp-home control has been used to protect the clutch from being overheated. In the limp-home mode, the temperature of the clutch is estimated to determine the overheating of the clutch. When the clutch is determined to be overheated, “odd to odd” or “even to even” driving control, namely single clutch driving, is performed. The single clutch driving does not control a shift stage in an input shaft provided with the overheated clutch.
However, we have discovered that, in the driving mode under the limp-home control, the single clutch driving brings a large power disconnection due to a large gear ratio shift during shifting to high or low stages, such that the driving performance by the single clutch driving is far below than the driving performance provided with the double clutch driving in which shifting is performed by using two clutches together. We have further discovered that the single clutch driving may not provide a reverse drive during the odd to odd shifting.